With the increase in the use of selective call systems, such as paging systems, for transferring information, the need for maintaining security while transferring information has developed. If a competitor were to find out the address of a selective call receiver, the communications could be received by the competitor at another selective call receiver. The increase in group calling whereby a message for all of the salesmen of a company comprising confidential information could be sent to a single address which multiple selective call receivers contain accentuates the need for secure communications. The message could be intercepted by a competitor utilizing the group address.
The military and some governmental authorities use encryption techniques for scrambling communications, but these techniques are typically costly and require additional components. The decrease in the size of selective call receivers and the decrease in the cost thereof has opened new markets for selective call communications, many of which are unwilling to carry bulky receivers or pay high costs but nevertheless would prefer the security of encrypted communications.
Thus, what is needed is a method and apparatus for encrypting and de-encrypting a selective call signal to prevent unauthorized perusal of the information encoded thereon.